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Dr. Joseph Cox (he/him) is a public health clinician and researcher. His work in biobehavioural surveillance (i.e., research that combines surveys and biological testing) began back in 2005 with the Argus study — a predecessor of the Engage study, which he leads in Montreal. Engage focuses on the sexual health of Two-Spirit, gay, bisexual, trans, and queer men (2S/GBTQ+) across three research sites based in Montreal, Toronto, and Vancouver.
A recent publication by the Engage Montreal team investigates the incidence and risk factors of syphilis, chlamydia, and gonorrhea among 2S/GBTQ+ and doxy-PEP prescribing criteria. Typically, STI occurrence research uses data from clinical cohorts, but the Engage study employs respondent-driving sampling to recruit participants from the broader community. Here, folks are invited to join the study through a voucher from someone who has already participated.
“Half the time, STIs are asymptomatic,” Dr. Cox says. “If you're only measuring infections because somebody presents to a clinic because of symptoms or for testing, you could be missing a lot. Community-based recruitment and testing gives us a better sense of what's going on.”
Using a community-based sample from three cities — Toronto, Montreal, and Vancouver — one finding reveals that roughly one third of urban 2S/GBTQ+ are going to experience at least one episode of syphilis, chlamydia, or gonorrhea in a year. Other findings are concerned with assessing the drivers of these three STIs. “Historically, a common STI driver was unprotected sex — there's a biological basis for it. But we want to go broader than that,” Dr. Cox says. With a more holistic view, the Engage team have considered newer phenomena for 2S/GBTQ+ as risk drivers —- like using HIV PrEP and engaging in chemsex and group sex. “These add to our appreciation of what could be important for 2S/GBTQ+ when we're thinking about prevention and care.”
The paper also identifies three targeted “prescribing criteria” for doxy-PEP, with the aim of contributing to the evidence base for the use of this medication. If taken within 72 hours after sex, doxycycline has been shown to prevent to varying degrees the aforementioned STIs. These criteria include having had an STI diagnosis in the past year, a greater number of sexual partners (≥ 10) in the past six months, and reporting the use of HIV-PrEP.
The effort to identify these criteria stems from concerns around anti-microbial resistance (AMR). Though doxy-PEP is effective and could bend the curve on STIs, AMR remains the biggest downside. “A big fear any prescriber recognizes is AMR,” Dr. Cox explains. “Are we contributing to more AMR? Are we also perhaps burdening a population already more affected by AMR?” For example, antimicrobial-resistant gonorrhea and shigella are already concerns for 2S/GBTQ+. Within this context, the idea behind these criteria is to inform the prescription of doxy-PEP: optimizing the use of this promising biomedical intervention, while also minimizing the potential harms associated with antimicrobial resistance.
Photo: Dr. Joseph Cox
"Though 2S/GBTQ+ men are a relative minority in the general population, they carry a disproportionate burden of HIV and other STIs. Knowing what’s happening with HIV and STI epidemics among this population has always been part of my role in public health, and in my interests as a researcher and a gay man. Public health has a responsibility to make sure people are getting the necessary prevention, testing, and treatment they need.”
